Acoustics and physics
Fundamental frequency
Also known as first harmonic, natural frequency (acoustic).
The fundamental frequency is the lowest natural resonant frequency of a vibrating system. For a sonic horn it is the nameplate frequency at which the diaphragm or piston is designed to oscillate and at which the horn delivers its rated SPL. A horn marked "60 Hz" produces a fundamental at 60 Hz plus a series of harmonics at integer multiples (120 Hz, 180 Hz, etc.).
Why it is the published number
Acoustic energy is concentrated at the fundamental. Harmonics carry progressively less energy. Selection charts, sizing tools and ROI calculations all use the fundamental as the reference. When tuning a multi-horn array, the fundamentals are chosen to avoid coincidence with vessel-tube resonance modes that could cause unwanted vibration.
Related terms
Related terms
- FrequencyFrequency is the number of acoustic cycles per second, measured in hertz. Industrial acoustic cleaners operate at 12–30 Hz (infrasonic), 60–250 Hz (low) or 250–450 Hz (high).
- HarmonicA harmonic is an integer multiple of the fundamental frequency. A sonic horn radiates energy mainly at its fundamental, with progressively less at higher harmonics.
- ResonanceResonance is the amplification that occurs when a driving frequency matches a natural mode of a system. It is exploited by sonic horns and avoided in tube-bank installation design.
- Diaphragm hornA diaphragm horn is a sonic horn whose sound is generated by a vibrating titanium or stainless-steel diaphragm driven by pulsed compressed air. The dominant form-factor for low-frequency industrial cleaning.